The invention relates to a porous, hygroscopic heat exchanger wall element and a method of manufacturing the same.
Swedish Patent Application No. 7606060-7 discloses a heat and humidity exchanger having porous, tubular partition wall elements, particularly in the form of textile felt hoses, which partition wall elements separate flow passages of two gas flows, particularly air flows, having different temperatures and/or humidity contents. The partition wall elements are vertically arranged and communicate at the top and the bottom with an upper and a lower salt solution bath, respectively, whereby the partition wall element is kept constantly drenched with salt in its pores so as to prevent the deposit of ice and impurities in and on the partition wall element.
Such an arrangement with two different salt solution baths is rather complicated and the object of the present invention is to achieve a heat exchanger wall element, where permanent salt solution baths are superfluous, but effective defrosting and purifying action is maintained. Furthermore, the heat conductivity through the wall element should be as good as possible, and the wall element, despite its porosity, should be tight enough to prevent the transfer of ill-smelling and unhealthy substances from one gas flow (e.g., exhaust air) to the other (e.g., inflow air) in the heat exchanger.